I have had good luck with the cast iron smoke boxes on my gasser. I soaked the chips good, and put them in. I used two boxs. Warm the grill with one to get it smoking, then put number two on with the meat. When smoke slows, I pull box one, and refill, and put back on. Keeps the smoke going a few hours that way.

Ditto the sepret smoker though. I just got a ECB and like it. Do the mods to it[at least the charcoal tray one] and for a little over $30 your ready to go.